Wheel and axle assembly having an entrapped thrust bearing

ABSTRACT

An improved low-friction carriage for a toy vehicle where the wheels are each of one-piece construction including an axle bearing surface and a precisely concentric outer running surface. The wheel is retained by blunting the end portion of the corresponding axle and press fitting a steel ball in another opening of the wheel to act as a thrust bearing. Not only is friction reduced, but the axle, the wheel and the steel ball are economical elements which are easily and inexpensively assembled.

United States Patent Parker et al.

154] WHEEL AND AXLE ASSEMBLY HAVING AN ENTRAPPED THRUST BEARING [72]Inventors: John C. Parker, Los Angeles; Keith M. Johnson, South Laguna,both of Calif.

[73] Assignee: Mattel, Inc., Hawthorne, Calif.

[22] Filed: Nov. 27, 1970 [21] Appl. No.: 93,348

[52] US. Cl. ..46/201, 29/1495, 29/453, 29/522, 46/221, 308/159 [51]Int. Cl. ..A63h 17/26 [58] Field of Search ..29/434, 443; 46/221, 222,223, 46/201 [56] References Cited UNITED STATES PATENTS 3,566,536 3/1971Baynes et a1 ..46/221 3,613,307 10/1971 Haynes et al ..46/221 51 Oct. 3,1972 1,975,083 [0/1934 Cavanagh ..46/201 3,510,981 5/1970 LaBrancheetal..46/221X FOREIGN PATENTS OR APPLICATIONS 824,916 12/1951 Germany.46/221 1,180,292 10/1964 Germany ..46/221 Primary Examiner-F. BarryShay AttorneySeymour A. Scholnick [5 7] ABSTRACT An improvedlow-friction carriage for a toy vehicle where the wheels are each ofone-piece construction including an axle bearing surface and a preciselyconcentric outer running surface. The wheel is retained by blunting theend portion of the corresponding axle and press fitting a steel ball inanother opening of the wheel to act as a thrust bearing. Not only isfriction reduced, but the axle, the wheel and the steel ball areeconomical elements which are easily and inexpensively assembled.

9 Claims, 4 Drawing Figures WHEEL AND AXLE ASSEMBLY HAVING AN ENTRAPPEDTI-IRUST BEARING BACKGROUND OF THE INVENTION 1 Field of the InventionThe present invention relates generally to toy vehicles and, moreparticularly, to a freely rotatable wheel and method for assemblywhereby the frictional forces acting upon the wheel when it is rotatedare reduced and the mode of assemblying the wheel to a vehicle minimizecosts.

2. Description of the Prior Art Small toy vehicles in the form ofautomobiles have become exceedingly popular. These vehicles generallyhave metal bodies suitably attached to a carriage with freely rotatablewheels mounted to very small diameter wire axles, as exemplified by U.S.Pat. No. 3,510,981 to H. W. La Branche et al. The great majority ofthese vehicles are propelled by the force of gravity therebynecessitating a starting position on a running surface at some levelvertically higher than the remainder of the running surface. Because thevehicles are propelled by the force of gravity, frictional forcesgenerated due to movement of the vehicle critically affect the vehiclessmaximum speed and distance of movement. Thus, it is of utmost importanceto have moving parts which keep the frictional forces or drag on thevehicle to a minimum.

To successfully mass market toy vehicles, it is necessary to minimizethe cost of manufacturing and assembly so as to be economicallyacceptable.

SUMMARY OF THE INVENTION The present invention fulfills the necessaryrequirements mentioned above and provides an improved toy vehiclecarriage comprising a support frame; at least two axles, one axleconnected to one end portion of the support frame and the other axleconnected to the other end portion of the support frame; at least fourwheels, two connected to each of the axles wherein each of the wheelsinclude an outer running surface, a first opening concentric with therunning surface for receiving an end portion of one of the axles, thesurrounding wall of the opening forming a bearing surface, and a secondopening aligned with the first opening for receiving a thrust bearingelement, the wheel being formed of resilient material; and at least fourspherical thrust bearings each entrapped within a second opening of oneof the wheels whereby a low-friction, lowcost carriage is provided. Theinvention further comprises the assembly including the wheel alreadydescribed, an axle and a spherical thrust bearing. Further, theinvention herein includes the wheel structure which is a unitary elementand the method by which the wheel is assembled and retained to an axle.

It is a general aim of the present invention to provide a toy vehiclecarriage with freely rotatable wheels which is inexpensive tomanufacture and to assemble.

Another aim of the present invention is to provide a toy vehiclecarriage of sufficient resiliency so as to relieve stress on theattached axles.

Another aspect of the present invention is to provide a wheel assemblyhaving a low-rolling friction which is simple in construction, reliablein operation, inexpensive to manufacture and exceedingly easy toassemble.

A corollary object of the present invention is to provide a toy vehiclewheel of high precision construction, especially the distance betweenthe outer running surface and the opening receiving the axle about whichthe wheel rotates and yet, be easily and cheaply manufacturable as aunitary element.

Still another aspect of the present invention is to provide a method ofassemblying a wheel to an axle with a minimum of material, machine andlabor costs.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of a toyvehicle carriage positioned on a track section.

FIG. 2 is a sectional elevational view of the toy vehicle carriage takenalong line 2-2 of FIG. 1.

FIG. 3 is a bottom plan view of the toy vehicle carriage of FIG. 1.

FIG. 4 is an enlarged elevational sectional view of a modified portionof the view shown in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT While the present invention issusceptible of various modifications and alternative constructions, anillustrative embodiment is shown in the drawing and will herein bedescribed in detail. It should be understood, however, that it is notthe intention to limit the invention to the particular forms disclosed;but, on the contrary, the intention is to cover all modifications,equivalents and alternative constructions falling within the spirit andscope of the invention as expressed in the appended claims.

Referring to FIG. I, there is illustrated a toy vehicle carriage 10positioned on a track section 12. The track section 12 represents aportion of a track layout having a number of track sections connectedend to end so as to provide a roadway for a toy vehicle. The tracksection includes a support portion 14 having a running surface 16 andtwo oppositely disposed obliquely extending guide flanges l8 and 20. Theguide flanges l8 and 20 guide the wheels of the toy vehicle to ensurethat the vehicle remain on the running surface 16. Two depending flanges22 and 24 form with a bottom surface 26, a channel-shaped receptacle toreceive a track section connector to allow the track section 12 to becon nected to an abutting track section or to various types of tracklayout accessories, such as curves, loops, jump ramps etc. The provisionof a track section as part of a roadway ensures the vehicle a smooth,flat surface over which it may travel thereby enhancing speed andreducing friction on the vehicle. A fuller explanation of the tracksection is found in U.S. Pat. No. 3,487,999 to A. W. B. Nash et al.

The carriage is comprised of a support frame 30, four embedded axles 32,34, 36 and 38, FIGS. 1 and 3, and four wheel assemblies 40, 42, 44 and46. It is contemplated that the support frame will be suitably attachedto a vehicle body (not shown) which may take the shape of a toyautomobile, a toy motorcycle, a toy train or any other toy form where itis desired to attach a wheeled mechanism to allow movement.

An important aspect of the present invention is to provide a wheel andwheel assembly which is simply constructed, inexpensively manufacturedand inexpensively assembled and yet, minimizes the friction generatedupon rotation of the wheel. Referring to FIG. 4, there is illustrated inmore detail the wheel assembly 46 which includes a one-piece wheelstructure 48 of a resilient material, such as a synthetic resin, havingan outer surface divided into a relatively smaller diameter wide portion50 and a larger diameter narrow portion 52 which includes the outerwheel surface making contact with the running surface 16, FIG. 1, of thetrack section 12. As pointed out in the above-mentioned La Branche etal. patent, drag on a vehicle is greatly reduced by making the contactbetween the vehicle and the track section running surface as small aspossible. Thus, the wheel assembly has a fairly small contact with therunning surface on which it moves, yet, has the appearance and style ofa very wide wheel which closely simulates real wide-body racing tiresenjoying current popularity.

The wheel 48 includes a central opening 54 having a cylindrical wall 56which acts as a bearing surface against the axle 38. Aligned with theopening 54 so as to have coincident central longitudinal axes is asecond opening 58 of a larger diameter than the opening 54 and alsohaving a generally cylindrically shaped surrounding wall 60. An interiorannular recess 62 is formed in the wall 60 at a slight distance from anouter lateral surface 64 of the wheel. A truncated conical surface 66connects the wall 60 of the larger opening 58 with the wall 56 of thesmaller opening 54. The opening 54 is made precisely concentric with therunning surface 52 so as to allow free rotation about the axle 38. Thisis achieved easily with the present wheel structure because it is moldedas an integral unit and does not require the alignment of a secondbearing element as disclosed in the above-mentioned La Branche et al.patent. To limit wheel lateral motion or motion parallel to thelongitudinal axis of the axle 38, an end portion 70 of the axle isexpanded such as by being swaged so as to have a larger dimension ordiameter than the diameter of the opening 54. Thus, movement of thewheel in a leftward direction, as viewed in FIG. 4, is prevented due tothe abutment of the expanded end portion 70 and the wall 66. It is notedthat the slope of the wall 66 and the geometry of the end portion 70 aresuch as to provide minimum area contact when abutment occurs; thisfeature minimizes frictional drag on the rotation of the wheel 48. Toadditionally ensure a minimum of generated friction, the end portion hasa substantially smooth end surface 72 which selectively comes intocontact with a spherical thrust bearing 74. The thrust bearing 74 may bea small steel ball and is located within the opening 58 and entrapped ina stationary position relative the wheel by the annular recess 62 so asto provide a spacing between the spherical bearing and the end surface72 of the axle. An annular lip 73 prevents the bearing from removingitself. Movement of the wheel in a rightward direction, as viewed inFIG. 4, is thus limited by the abutment of the flat surface 72 and thesurface of the spherical bearing. Because the contact between thesurface 72 and the spherical bearing is intermittent, friction isminimized, and when contact does occur, it is along a fairly small areaof the spherical bearing and the flat end surface of the axle so as toadditionally minimize friction generated. It is noted that a spacing 75is provided between the thrust bearing and the end surface of the axleso that friction generating contact is not continuous between theseelements; contact occurs only when lateral forces move the wheel to theright.

To further ensure a minimum of friction being generated by the rotationof the wheel, a suitable silicone emulsion may be applied to the spacingbetween the bearing wall 56 and the axle 38.

The ease of manufacture is achieved by the fact the wheel 48 is of aone-piece construction. Assembly of the wheel and the axle is alsoeasily and economically accomplished by simply passing the axle throughthe opening 54 until the end portion '70 of the axle is within thespacing 58. The end portion is then swaged to expand its dimensionthereby locking in one axial direction the position of the wheel. Next,the spherical thrust bearing 74 is press fitted into the opening 58until engagement is made with the annular recess 62. Since the materialof the wheel is resilient, the thrust bearing may be easily andmechanically inserted with the wheel material springing back to itsoriginal form to ensure a locking engagement of the thrust bearing inthe wheel. Each of the other wheel assemblies 40, 42 and 44 aresimilarly constructed and assembled. it is noted that the thrustbearings not only perform a functional role but also an aesthetic roleby providing an attractive appearance to each of the wheel assemblies.

The structure of the wheel and the use of spherical bearings areinexpensive; that is, the wheel is easily and economically formed by aone-step molding operation and steel balls with known dimensionaltolerances are readily available. Further, the steel ball is very easyto handle, feed and insert using known production assembly eq uipment.

Another important aspect of the present invention is achieved by theprovision of the resilient support frame 30 which reduces the stressinduced in the axles. As mentioned, the axles are of very small diameterwire and therefore, unable to carrying excessive bending loads.Referring to FIGS. 2 and 3, the support frame 30 is comprised of aunitary piece of synthetic resin which is suitably molded to a desiredshape. For example, the support frame includes a U-shaped end portionfor supporting the wheel assemblies 44 and 46 and a U- shaped endportion 82 for supporting the wheel assemblies 40 and 42. Connecting thetwo U-shaped end portions is a central elongated portion 84. In theparticular embodiment disclosed, there are four axles as alreadymentioned, 32, 34, 36 and 38 each of which is embedded in acorresponding end portion, such as the axles 36 and 38 being embedded inthe end portion 80 while the axles 32 and 34 are embedded in the endportion 82. The support frame 30 may be molded as a unitary piece in theshape shown, and the axles may he embedded by providing the placement ofthe axles within the mold before the heated synthetic resin is injected.This may be accomplished by initially providing the axles 32 and 34 as asingle strand of wire with the central portion illustrated in dottedline and designated 86 being removed after the support frame has cooledand been removed from the mold. The axles 36 and 38 may be embedded in alike manner. It is to be understood, however, that the particular formof the support frame is not to be considered as limiting the inventionherein. For example, the support frame may simply comprise an elongatedstrip of synthetic resin material with a strand of small diameter wireembedded at either end to form the four axles needed for a toyautomobile. it is to be further understood that more than one wheel maybe mounted at each axle if the toy vehicle simulates a real vehiclehaving multiple wheels at an axle.

It is contemplated that the support frame will be attached to a vehicleat or about a lateral lug 88 integral with the central portion 84 sothat the two legs of the U-shaped end portions are flexible in responseto forces being applied to the wheel so as to reduce the stressesinduced in the axles.

We claim:

1. A toy vehicle carriage comprising:

a support frame;

at least one axle connected to said support frame and having an outerend with means for retaining a wheel thereon;

a wheel mounted to said axle for abutment with said retaining means,said wheel including an outer running surface, a first openingconcentric with said running surface surface for receiving an endportion of said axle, the surrounding wall of said opening forming abearing surface, and a second opening aligned and communicating withsaid first opening for accommodating therein said retaining means andfor receiving a thrust bearing element, said wheel being formed ofresilient material; and

a spherical thrust bearing entrapped within said second opening of saidwheel whereby said retaining means is trapped between said thrustbearing and a portion of said wheel.

2. A toy vehicle carriage, as claimed in claim 1,

wherein:

said first opening of said wheel is cylindrically shaped; and

said retaining means comprises an expanded end portion having a largerdiameter than said first opening whereby said wheel is restrained inmovement in a direction parallel to the longitudinal axis of said axle.

3. A toy vehicle carriage, as claimed in claim 2,

wherein:

said second opening of said wheel is surrounded by a wall having aninner recess to receive and entrap said spherical thrust bearing; andsaid expanded end portion of said axle is positioned within said secondopening so as to provide a spacing between said end portion and saidthrust bearing.

4. A toy vehicle carriage, as claimed in claim 3,

wherein said support frame is resilient.

5. A toy vehicle carriage, as claimed in claim 4, wherein said axle isembedded within said resilient support frame.

6. A toy vehicle carriage, as claimed in claim 5, wherein said wheelincludes an outer surface having a wide smaller diameter, non-runningportion and a narrow larger diameter portion including said outerrunning surface.

7. A toy vehicle wheel assembly comprising:

a wheel having an outer running surface, a first cylindrical openingconcentric with said running surface for receiving an axle, thesurrounding wall of said opening forming a bearing surface, and a secondopening aligned and communicating with said first o e in rust bearinelement in said second op niiiggthrust bearl ng element having adiameter greater than a portion of the wall which forms said secondopening for entrapment of said thrust bearing element in said secondopening, said whee] being resilient enough to permit said thrust bearingelement to be forced into said second opening behind said wall portionthereof; and i an axle positioned within the first opening and having anenlarged end portion of diameter greater than the diameter of said firstopening.

8. A wheel assembly, as claimed in claim 7, wherein the wall surroundingsaid second opening has an inner recess to receive and entrap saidthrust bearing element so as to provide a spacing from the enlarged endportion of said axle.

9. A wheel assembly, as claimed in claim 8, wherein said wheel is aunitary element formed of a resilient material; and said thrust bearingelement is spherical.

1. A toy vehicle carriage comprising: a support frame; at least one axleconnected to said support frame and having an outer end with means forretaining a wheel thereon; a wheel mounted to said axle for abutmentwith said retaining means, said wheel including an outer runningsurface, a first opening concentric with said running surface surfacefor receiving an end portion of said axle, the surrounding wall of saidopening forming a bearing surface, and a second opening aligned andcommunicating with said first opening for accommodating therein saidretaining means and for receiving a thrust bearing element, said wheelbeing formed of resilient material; and a spherical thrust bearingentrapped within said second opening of said wheel whereby saidretaining means is trapped between said thrust bearing and a portion ofsaid wheel.
 2. A toy vehicle carriage, as claimed in claim 1, wherein:said first opening of said wheel is cylindrically shaped; and saidretaining means comprises an expanded end portion having a largerdiameter than said first opening whereby said wheel is restrained inmovement in a direction parallel to the longitudinal axis of said axle.3. A toy vehicle carriage, as claimed in claim 2, wherein: said secondopening of said wheel is surrounded by a wall having an inner recess toreceive and entrap said spherical thrust bearing; and said expanded endportion of said axle is positioned within said second opening so as toprovide a spacing between said end portion and said thrust bearing.
 4. Atoy vehicle carriage, as claimed in claim 3, wherein said support frameis resilient.
 5. A toy vehicle carriage, as claimed in claim 4, whereinsaid axle is embedded within said resilient support frame.
 6. A toyvehicle carriage, as claimed in claim 5, wherein said wheel includes anouter surface having a wide smaller diameter, non-running portion and anarrow larger diameter portion including said outer running surface. 7.A toy vehicle wheel assembly comprising: a wheel having an outer runningsurface, a first cylindrical opening concentric with said runningsurface for receiving an axle, the surrounding wall of said openingforming a bearing surface, and a second opening aligned andcommunicating with said first opening, a thrust bearing element in saidsecond opening, said thrust bearing element having a diameter greaterthan a portion of the wall which forms said second opening forentrapment of said thrust bearing element in said second opening, saidwheel being resilient enough to permit said thrust bearing element to beforced into said second opening behind said wall portion thereof; and anaxle positioned within the first opening and having an enlarged endportion of diameter greater than the diameter of said first opening. 8.A wheel assembly, as claimed in claim 7, wherein the wall surroundingsaid second opening has an inner recess to receive and entrap saidthrust bearing element so as to provide a spacing from the enlarged endportion of said axle.
 9. A wheel assembly, as claimed in claim 8,wherein said wheel is a unitary element formed of a resilient material;and said thrust bearing element is spherical.